The average national survival rate after out-of-hospital cardiac arrest and standard CPR is less than 5%. Simple and effective methods for improving the efficacy of CPR are needed. The inspiratory impedance threshold valve (ITV) is an innovative device designed to significantly increase the effectiveness of standard CPR in patients by increasing negative intrathoracic pressure and venous blood return to the heart. Preliminary animal studies with the ITV demonstrate up to 100% increase in vital organ perfusion and normalization of cerebral blood flow during standard CPR in an animal model. This phase 1 investigation proposes to a) improve the safety and efficiency of the ITV by making and evaluating bioengineering design changes in the valve and b) determine proof of concept by assessing neurologically intact survival rates and pulmonary complication rates with and without the ITV during standard CPR in a porcine model of cardiac arrest. If successful, the phase 2 studies will address the potential clinical efficacy of the ITV in patients with out-of-hospital cardiac arrest. Use of the ITV is expected to increase patient resuscitation rates by 25-50%, based upon the improvement in blood flow to the heart and brain observed in animal studies. If a significant clinical benefit is demonstrated, the ITV would become a standard piece of resuscitation equipment for all patients in cardiac arrest who receive CPR. PROPOSED COMMERCIAL APPLICATIONS: The Resusci-Valve ITV has significant worldwide market and commercialization potential due to several factors including: its innovative qualities, low cost, ease of use with minimal training, and compatibility with any standard breathing circuit. The potential market size for the ITV is substantial as there are at least 750,000 patients treated for cardiac arrests per year in the United States alone. The ITV can be added easily to all existing Basic and Advanced Life Support resuscitation equipment.